Aa
I love Symfony but my eyes aren't well synced - should I redo one, or wait & hope?
I'm one of the first lucky US recipients of the Symfony lens. The first one (L) gave me almost perfect near-to-far vision, with a slight strain up close. So we changed the R prescription by .5, for micro-monovision which would be better for reading. Surgery on the R eye was 2 weeks later. To my shock, the difference came out 1.5 instead of .5 -- my R eye can only see clearly for 4-5 feet. With both together, it's still life-changing: first thing in the morning, with L eye dominant, I can see for miles & miles. But after a couple hours at the computer screen, my blurrier R eye takes over, & they never re-sync. Intermediate's OK, but for theater, concerts, walking around, driving, etc., the combo of myopia + haloes is annyoying & worrisome. (I too have porcupines around white lights & concentric circles around red lights.)
My doctor has scheduled an explantation & replacement for 2 weeks from now. My second opinion said If t'were done, t'were best done quickly -- preferably within 4-6 weeks. But, @softwaredeveloper, you noted that neuroadaptation reportedly takes longer with the Symfony.
So my question is: Should I give it more time, & risk closing the window of max safety, or do it ASAP, & risk a more dangerous operation, worse potential complications, longer recovery time, & no guarantee of achieving the near-perfect result which right now appears tantalizingly almost within reach?
My doctor has scheduled an explantation & replacement for 2 weeks from now. My second opinion said If t'were done, t'were best done quickly -- preferably within 4-6 weeks. But, @softwaredeveloper, you noted that neuroadaptation reportedly takes longer with the Symfony.
So my question is: Should I give it more time, & risk closing the window of max safety, or do it ASAP, & risk a more dangerous operation, worse potential complications, longer recovery time, & no guarantee of achieving the near-perfect result which right now appears tantalizingly almost within reach?
Your lens is focusing at the wrong distance, which is a refractive error. Neuroadaptation doesn't change the point at which the lens is focused at. The lens can change position during the first few weeks of healing, and change the focal point, which is why they tend to wait 3-4 weeks for vision to stabilize before prescribing glasses for any residual refractive error (Or even 6-8 weeks, or more months in rarer cases where the refraction hasn't stabilized). Since laser correction is permanent they usually tend to be more cautious and wait longer before using that.
The effective lens power is depends on both the power of a lens and its location. It sounds like they predicted the lens would be at a different location, so it is the wrong lens power for where the lens wound up settling. From your perspective it doesn't matter whether they predicted the location of the lens wrong, it still means you've got the wrong lens power, and neuroadaptation can't fix that. At most it can give you some level of improved vision despite the lens being focused at the wrong point.
What I've read suggests that usually with the Symfony or multifocal lenses people have decent distant vision after surgery and that the impact of neuroadaptation is mostly providing better near vision over time. There may be some improvement in distance vision over time, but its likely minor and regardless doesn't relate to the distance your lens is focused at.
Whether to do a lens exchange vs. laser enhancement depends on the patient's details like the state of the capsular bag and its stability, and the surgeon's preference. There is some risk that the replacement lens might not be in the exact position they expect either, and that risk depends on the reasons they see why this lens isn't located where they expected it to be, which can leave the power still off a bit. It seems likely they'll be fairly accurate though if they are recommending it as an option. Similarly, laser correction is fairly accurate (though not exact, partly because of variation in how people's eyes heal afterwards), though I haven't seen good statistics on how accurate small tweaks are.
Most of the information out there on laser correction is focused on the accuracy of the large corrections of several diopters that most people get, since most people getting laser surgery are doing it because they have high prescriptions. The error in a correction seems to be mostly a % of the attempted correction, i.e. so a small 1 diopter correction will lead to a smaller absolute error than a 10 diopter correction. I don't know if there are good studies on small tweaks or not, I hadn't taken much time to search for it.
Laser correction of the cornea doesn't leave it as smooth as the surface of an artificial lens, though it is getting better all the time and small changes leave it fairly regular. The potential irregularity is why with multifocals (less so the Symfony) ther is some concern over people who had laser correction that left the surface irregular, but that is mostly a concern for those who had large corrections and those who had it done with older laser techniques.
If you look closely at a TV or computer screen you'll see the pixel dots, and the image won't seem as high quality. The more dots per inch, the higher the quality. Just as displays have gotten higher resolution (4k TVs and "retina" phones/tablets and other screens), laser surgery has gotten better over the years, the equivalent of more dots per inch. You don't actually see dots in the case of laser correction, but the point is that artificial lenses like IOLs are manufactured to make the surface continuous and higher quality than a laser correction can be. The very small risk is whether the irregularity on the cornea from laser correction reduces "best corrected" vision at all. Unfortunately I hadn't seen statistics on what the risks are with small laser tweaks, since even if they are tiny, they are worth considering when debating whether to use that vs a lens exchange (someone winds up being the "statistic" even with rare occurrences). I think doctors at this point are relying more on their subjective judgement than objective figures.
With a high enough resolution "retina display" you won't see the pixels, so their existence is academic. The question is whether laser correction for small tweaks is equivalently precise, if the risk of lowering visual quality is low enough.
The effective lens power is depends on both the power of a lens and its location. It sounds like they predicted the lens would be at a different location, so it is the wrong lens power for where the lens wound up settling. From your perspective it doesn't matter whether they predicted the location of the lens wrong, it still means you've got the wrong lens power, and neuroadaptation can't fix that. At most it can give you some level of improved vision despite the lens being focused at the wrong point.
What I've read suggests that usually with the Symfony or multifocal lenses people have decent distant vision after surgery and that the impact of neuroadaptation is mostly providing better near vision over time. There may be some improvement in distance vision over time, but its likely minor and regardless doesn't relate to the distance your lens is focused at.
Whether to do a lens exchange vs. laser enhancement depends on the patient's details like the state of the capsular bag and its stability, and the surgeon's preference. There is some risk that the replacement lens might not be in the exact position they expect either, and that risk depends on the reasons they see why this lens isn't located where they expected it to be, which can leave the power still off a bit. It seems likely they'll be fairly accurate though if they are recommending it as an option. Similarly, laser correction is fairly accurate (though not exact, partly because of variation in how people's eyes heal afterwards), though I haven't seen good statistics on how accurate small tweaks are.
Most of the information out there on laser correction is focused on the accuracy of the large corrections of several diopters that most people get, since most people getting laser surgery are doing it because they have high prescriptions. The error in a correction seems to be mostly a % of the attempted correction, i.e. so a small 1 diopter correction will lead to a smaller absolute error than a 10 diopter correction. I don't know if there are good studies on small tweaks or not, I hadn't taken much time to search for it.
Laser correction of the cornea doesn't leave it as smooth as the surface of an artificial lens, though it is getting better all the time and small changes leave it fairly regular. The potential irregularity is why with multifocals (less so the Symfony) ther is some concern over people who had laser correction that left the surface irregular, but that is mostly a concern for those who had large corrections and those who had it done with older laser techniques.
If you look closely at a TV or computer screen you'll see the pixel dots, and the image won't seem as high quality. The more dots per inch, the higher the quality. Just as displays have gotten higher resolution (4k TVs and "retina" phones/tablets and other screens), laser surgery has gotten better over the years, the equivalent of more dots per inch. You don't actually see dots in the case of laser correction, but the point is that artificial lenses like IOLs are manufactured to make the surface continuous and higher quality than a laser correction can be. The very small risk is whether the irregularity on the cornea from laser correction reduces "best corrected" vision at all. Unfortunately I hadn't seen statistics on what the risks are with small laser tweaks, since even if they are tiny, they are worth considering when debating whether to use that vs a lens exchange (someone winds up being the "statistic" even with rare occurrences). I think doctors at this point are relying more on their subjective judgement than objective figures.
With a high enough resolution "retina display" you won't see the pixels, so their existence is academic. The question is whether laser correction for small tweaks is equivalently precise, if the risk of lowering visual quality is low enough.
3 Comments
Thanks, SD. This parallels the discussion my surgeon & I had, partly thanks to your past posts. He's discussed it with the Symfony rep & sounds convinced he can replace the lens more precisely in the right spot, with the advantage of not permanently altering the cornea...although I'm guessing a replaced lens is nearly as permanent, given the risks of further surgery.
You should consider going with your original surgeon recommendation as waiting will not change the glasses RX in RE which seems to be the biggest problem for your.
4 Comments
I'm not sure what you're saying? Maybe I didn't give enough info. My surgeon's original rec. was wait 3-4 months & see if anything changes. I thought my blurred R vision (which hasn't changed in 5 weeks) was due to a wrong lens, & asked him to switch it. He agreed, but said the unexpected result is due to where the lens settled, not its power. He said we could go with either Lasik or explantation/replacement, but I'd probably be happier with switching.
It seems that both your surgeon and your second opinion have recommended IOL exchange which you have scheduled in 2 weeks. and that the date of your exchange falls within a 'reasonable" period of time post-op to satisfy both your surgeon and your consultant. So it would appear the course you've mapped out is acceptable to both of the surgeons that have examined your eye.
Thank you!
Sure and best of luck.
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